A cup gun for the above-mentioned uses is known from the instruction manual “Tribo Becherpistole PEM-TG3” as of April 2006, no. 0351716, which is published on the Internet as prior art and is distributed by Wagner GmbH under product no. 0351036. FIG. 1 is taken from the instruction manual and shows a three-dimensional view of the cup gun D. The cup gun D is a manually actuatable powder spray gun with a powder storage container H, which is screwed from above onto the gun D in the rear region. The cup gun D has a screw thread J for this purpose.
A similar cup gun operating with triboelectric charging is known from the service manual “Hand- and Automatikpistolen” June 2006 edition, no. 0351883, page 121 et seq which is likewise published on the Internet as prior art.
Lastly, a powder cup gun operating with corona charging (high voltage) is known from the instruction manual “Pulver Becherpistole PEM-CG4-HiCoat”, February 2007 edition, no. 0390821.
These cup guns have the common feature that they have an electrical connection G and a supply connection F for compressed air at the lower end of the hand grip. The electrical connection G is connected to a control unit via an electrical cable, and the supply connection F is connected to a control unit via a compressed air tube. The compressed air supply to the cup gun can be adjusted with the aid of the control unit. These cup guns have the disadvantage however that a colour change cannot be implemented quickly enough. The user has to first carefully unscrew the storage cup from the gun. To this end, he holds the gun with one hand and takes hold of the cup with the other hand and starts to unscrew it. He will generally grasp the cup a number of times in order to be able to unscrew it completely. However, it is awkward to grasp around the cup, in particular if there is still powder in the storage cup, because there is then a risk that the powder will be spilled or will trickle out from the outlet opening of the powder cup.
With the above-described powder cup guns, the compressed air supplied to the gun via the supply connection is divided into a conveying air, a tribo air, (in the case of tribo guns) or an atomising air (in the case of corona guns), a metering air and an air for fluidising the powder. To this end, a manually adjustable valve for the conveying air, a manually adjustable valve for the metering air, a manually adjustable valve for the atomising air or tribo air, and a manually adjustable valve for the fluidising air are located to the rear on the powder cup gun. All valves are connected on the input side to the supply connection. If a valve is then adjusted, it is not possible to ensure that this has no effect on the other airflows. The actual magnitude of the four air pressures is unknown to the user. The four valve settings give only rather inaccurate information regarding said air pressures. This in turn means that it is not easily possible to make recommendations as to how the individual air pressures are to be set in other powder spray guns, in particular in powder spray guns used in batch production. The results achieved are thus only reproducible to a limited extent, and the compressed air settings are not easily transferrable to other spray guns. This is desirable however, inter alia with the development of coating powder.